Firebox size and heating area

Feb 2, 2016
99
central iowa
Can I get some of you guys with downdraft gassers to share the dimensions of your primary firebox and the amount of area you are heating?
I am in the design phase of building a gasser and would like to not way over or way undersize the thing, main factor is for material costs.
 
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E Yoder

Feeling the Heat
Jan 27, 2017
374
Floyd, VA
You're going to want to match the nozzle size, firebox volume and fan/draft. It's pretty tricky from what I've heard if you want it as clean burning as the commercially produced units.
The HeatMaster unit I ran the last 3 years has approx 19x19x31" firebox. Heating about 3300 sq ft, maxed that little stove out.
 

maple1

Minister of Fire
Sep 15, 2011
10,483
Nova Scotia
This is almost an impossible question.

As pointed out above, way more variables in burn efficiency than firebox size.

And area being heated has way too many variables to try to factor in generally. Overall climate, heat loss, difference in daytime temps from day to day or week to week, whether the sun is out or not, whether the wind is blowing or not, on it goes. Which storage capacity can make all go away.

You might be able to half-guess, by running BTU/hr heat loss calcs on what you are heating on a given day, then converting that to pounds then volume of wood BTU-equivalent for volume of wood on a given day, while factoring in maybe a 60-70% efficiency factor, then dividing by how many times a day you want to be loading. If you don't have storage though, that means smolder time, then bigger loads = more inefficiencies to try to account for. Light loads usually means smaller more frequent fires - so you could always load a bigger box lighter.

My indoor gasser with storage holds about 3 cu.ft.. And it burns around 5-6 hours a day mid-winter, two loads not quite full.
 
Feb 2, 2016
99
central iowa
Thanks @maple1 I do realize there are tons of variables and I am just winging it, I have 1500gal of storage so that is a help and I know how big my primary is, it figures out to about the 24x24x24 I am wanting to build and does the job in about 4-6 hours in mid winter, takes about 4 loads to get there so assuming I get the new one to work right I should pick up more efficiency and therefore cut number of loads down at least, probably not time but....that is part of the improved efficiency of the gasser over my non conventional setup that I am running.
 
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salecker

Minister of Fire
Aug 22, 2010
1,081
Northern Canada
Why not copy a proven design?
The chinese do it all the time successfully,and profit from their copying.
 
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Feb 2, 2016
99
central iowa
@salecker you have a point, I don't have any around here to copy, The only gasser I know of anywhere around is huge and heating almost 7000sqft, I sure dont need that much. If I could find another one within reasonable driving rang I could study I would
 

E Yoder

Feeling the Heat
Jan 27, 2017
374
Floyd, VA
I would think Iowa would have quite a few outdoor gassers around. ? No telltale smoke plume though. :)
How to find someone that would let you look it over in great detail might be tough.
 

salecker

Minister of Fire
Aug 22, 2010
1,081
Northern Canada
I would think Iowa would have quite a few outdoor gassers around. ? No telltale smoke plume though. :)
How to find someone that would let you look it over in great detail might be tough.
No teltale smoke from Gassers.That is the beauty of the design.Not wasting BTU'S like the outdoor smoke dragons you would be looking for.
 

E Yoder

Feeling the Heat
Jan 27, 2017
374
Floyd, VA
I was referring to the newer style outdoor boilers like Central's Edge, Heatmaster G series, Crown's Pristine. All are downdraft gassers and fairly common now in the Midwest, but kind of unnoticed due to lack of smoke.
 

salecker

Minister of Fire
Aug 22, 2010
1,081
Northern Canada
But are they boilers or water heaters?
 
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brenndatomu

Minister of Fire
Aug 21, 2013
5,062
NE Ohio
But are they boilers or water heaters?
Are any of them actually "boilers"? I don't know that I have even seen/heard of a wood fired boiler (making steam) being used for private/residential use...
 

maple1

Minister of Fire
Sep 15, 2011
10,483
Nova Scotia
Are any of them actually "boilers"? I don't know that I have even seen/heard of a wood fired boiler (making steam) being used for private/residential use...
My line of thinking also. I don't imagine anyone here is using an actual 'boiler' per se, and actually boiling water, but 'boiler' is usually a lot easier to say than 'hydronic heater'.
 
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E Yoder

Feeling the Heat
Jan 27, 2017
374
Floyd, VA
Yes, it's not an accurate term, but commonly used. Oil and gas boilers at the typical 15 psi and 180F aren't boilers either.
The English language is pretty sloppy. :)
 

hedge wood

Member
Mar 1, 2009
113
Eastern NE
Thanks @maple1 I do realize there are tons of variables and I am just winging it, I have 1500gal of storage so that is a help and I know how big my primary is, it figures out to about the 24x24x24 I am wanting to build and does the job in about 4-6 hours in mid winter, takes about 4 loads to get there so assuming I get the new one to work right I should pick up more efficiency and therefore cut number of loads down at least, probably not time but....that is part of the improved efficiency of the gasser over my non conventional setup that I am running.
I am guessing but it sounds like your burning your current home made unit full tilt during a burn and putting the BTU'S in your 1500 gallon storage. I would wonder if you will pickup enough efficiency building a gassier to make it worth while for the time and money building it. Look others have said lots of good drawing on the net of current gassier's why wouldn't you just copy one. I do have a Garn 2000 in eastern Nebraska if you wanted to see one in person.
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,062
NE Ohio
We have a 650k BTU hydronic heater at work that operates at 25-30 PSI, which is technically considered "high pressure" but the state inspector has always let us operate it as "low pressure" as far as licensing and annual inspection details. We do have a licensed high pressure operator on staff though, if they ever get snippy about things.
 

salecker

Minister of Fire
Aug 22, 2010
1,081
Northern Canada
My understanding is if it operates under pressure it is a boiler,if it is unpressurized it is a water heater.
Please correct me if i am wrong,this is information that i have received on Hearth
 

maple1

Minister of Fire
Sep 15, 2011
10,483
Nova Scotia
I think I have seen everything that heats water called a boiler on here, pressurized or not. Called a boiler everywhere, actually, even in real life. Some might have come along & tried correcting people, that it is really a hydronic heater and not a boiler - but likely didn't get far with it. Right or wrong. :)
 
Feb 2, 2016
99
central iowa
I am guessing but it sounds like your burning your current home made unit full tilt during a burn and putting the BTU'S in your 1500 gallon storage. I would wonder if you will pickup enough efficiency building a gassier to make it worth while for the time and money building it. Look others have said lots of good drawing on the net of current gassier's why wouldn't you just copy one. I do have a Garn 2000 in eastern Nebraska if you wanted to see one in person.
The garn is a sweet idea but since I already have the storage in place I dont really want to go to a garn, thank you for the offer though. So I am basically copying the EKO design, however I am thinking I am going to use Born2Burn's air preheat design, I really like how he did that and it makes good sense to me, as far as building to gain efficiency I look to gain some just by increasing the fire tube length and number, I also have no real choice but to build one, cant afford to buy and old unit has developed a leak after 12 years, and the first 8-9 years being run in very poor manner to say the least.
 
Feb 2, 2016
99
central iowa
@E Yoder not a huge amount of wood burners in my area, I am too close to Des Moines and the town folks around here are to lazy to burn wood, most of the farmers dont either, to them it is easier to use propane. the boilers that are around are all smoke dragons except the one. the mentality around here is still huge firebox shove a whole tree in and let it go, " I can get 14 hours out of a load". Sorry to say my dad is that way too, I am not so worried about the smoke issue as I dont like to wast wood, e3ven though I get logs delivered for free it is still a fair bit of work to process.
 
Feb 2, 2016
99
central iowa
As far as cost to build this thing, with the current plan I am looking at about 700-800 USD in materials, my time to weld is something I am discounting because I enjoy doing that kinda of stuff and have lost pretty much all interest in working on machines for the neighbors, one I do not have the electronic tools required now days and two they are always in a huge A hurry and think you should work all night after working a day job. I am lucky to have a friend that owns a welding and sells me material at his cost plus will break stuff and CNC plasma cut for beer, and I have a large plasma cutter and a big Esaab wire feed welder.
 

Drewby

New Member
Aug 20, 2018
39
LaCrosse wi
@salecker you have a point, I don't have any around here to copy, The only gasser I know of anywhere around is huge and heating almost 7000sqft, I sure dont need that much. If I could find another one within reasonable driving rang I could study I would
I have both a wood gun E 100 that I’m in the process of refurbishing and also an Econoburn 100 that is also all torn apart waiting for an overhaul.
I have not operated either one but I’m in the process of cleaning them both up and getting them going again. I may be able to answer some questions and show you some pics if you want.
 
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